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Sodium bicarbonate for runners: what's being used and what the research says

We report what runners are using and what the research says. We don't recommend taking any supplement. Talk to your GP or a registered sports dietitian before trying one.

Quick answer

Research suggests a small benefit in hard efforts of about 30 seconds to 12 minutes across sports[1]. Bicarb buffers the acid these efforts produce[1]. But a 2025 meta-analysis of running trials, mostly under 5 minutes, found the benefit negligible once likely publication bias was allowed for, and stomach upset was common[2].

Research
Emerging (proposed)Clear in short, hard efforts across sports. In running-only trials, mostly under 5 minutes, the adjusted benefit was negligible.
Proposed by our editor; not yet confirmed by an expert reviewer.
WADA status
Permitted
Distances in the research
800 m–5K: studied10K–half: limited researchMarathon: not studiedUltra: not studied

What is sodium bicarbonate?

Bicarbonate is made by the body and is a central part of the body's main pH buffering system[3]. Sodium bicarbonate dissolves readily in water, including stomach acid, splitting into sodium and bicarbonate; some of the bicarbonate reacts with stomach acid to form carbon dioxide[1]. Taking it before exercise raises the level of bicarbonate in the blood; across studies of buffering supplements, it rose by about 5 mmol per litre on average[4].

Studies have given it as a powder in water, juice or a flavoured drink, or in capsules[2]. Newer forms include enteric-coated capsules, which resist dissolving in the stomach[5], mini-tablets in a carbohydrate hydrogel[6] and a lotion rubbed into the skin[7]. It is also an ingredient in some medicines, including antacids[1][8].

The Australian Institute of Sport puts it in Group A of its supplement framework, meaning strong scientific evidence for use in specific situations in sport, using evidence-based protocols[3].

Also called: bicarb, sodium hydrogen carbonate, NaHCO3.

Why is bicarb getting attention?

Bicarb is one of only a handful of performance supplements, along with caffeine, creatine, nitrate and possibly beta-alanine, that the IOC consensus statement says have good evidence behind them[9]. A 2021 ISSN position stand concluded that it improves high-intensity running, cycling, swimming and rowing[1]. Runners were there from the start: the first published study, in the 1930s, gave one person 10 g before treadmill running[1].

Its main drawback is stomach upset, and newer ways of taking it are being studied to reduce that, including enteric-coated capsules and mini-tablets inside a carbohydrate hydrogel[10]. In a 2024 trial, cyclists using the hydrogel form rode a 40 km time trial faster, with no significant difference in stomach symptoms from a placebo[6].

We found no survey measuring how many runners use it. Among 66 team-sport practitioners in the UK and US, 91% knew of bicarb but only 33% of those used it, and worry about stomach side effects was the most common barrier[11].

The claims, checked against the research

  • Faster 400 m to 1500 m racesMixed

    Small trials in trained runners found faster times: 1.52 seconds over 400 m[12], 2.9 seconds over 800 m[13] and about 3 seconds over 1500 m[14]. A 600 m trial in women found no significant difference[15], and pooled running trials showed a negligible benefit after adjustment for bias[2].

  • Faster 5K and 10K racesMixed

    We found no trial that timed a 5K or 10K race. Elite orienteers ran a 3.5 km time trial 6 seconds faster[16], but after 30 minutes at a hard pace, bicarb did not help trained runners last longer[17][18].

  • A stronger finishing kickMixed

    In cyclists, bicarb taken before and during a 3-hour simulated race raised power in a final 90-second sprint by about 3%[19]. The orienteers' gain came in the second half of their 3.5 km[16]. We found no running trial of a sprint finish.

  • Better interval sessionsMixed

    Over three 30-second running sprints, bicarb raised average speed in the third only[1]. After 20 treadmill repeats of 24 seconds, 8 men saw no significant difference in a final run to exhaustion[20].

  • Bigger gains from trainingMixed

    Women who took bicarb before 8 weeks of cycle interval sessions gained more in lactate threshold and time to fatigue than a placebo group[21]. Other training studies were mixed, and the ISSN says much more work is needed[1].

  • Help in a marathon or ultraNot studied

    We found no controlled trials in marathon or ultra running; the running tests in the 2025 meta-analysis lasted 1 to 30 minutes[2].

  • Extra gains with beta-alanineMixed

    In a meta-analysis of beta-alanine studies, taking it with bicarb gave the largest effect against placebo: 0.43, against 0.18 for beta-alanine overall[22]. Several studies found no added benefit from combining them[1].

  • Extra gains with caffeineMixed

    Only 1 of 8 studies found that combining caffeine and bicarb helped more than either alone[23]. The ISSN calls the combination's effect unclear[1].

How does bicarb work?

Hard running produces acid in the working muscles, and that build-up is linked to fatigue in efforts lasting a few minutes[1]. Bicarbonate in the blood acts as a buffer outside the muscle, which helps the muscle manage its own acid levels[9]: a higher level in the blood draws acid and lactate out of the working muscle, so energy can be produced quickly for longer[1].

Efforts under about 30 seconds rely mainly on phosphocreatine, while efforts of about 30 seconds to 5 minutes build up a lot of lactate and acid[1]. That fits where the effects are clearest: hard efforts of about 30 seconds to 12 minutes[1].

Researchers have suggested that a rise in blood bicarbonate of about 5 mmol per litre makes a benefit more likely[1]. In one study, 0.3 g per kg raised it by 6.0 to 12.3 mmol per litre depending on the person, against 2.0 to 5 after 0.1 g per kg[24].

It is a buffer, not a fuel, and the ISSN notes that longer, lower-intensity efforts, which build up less acid, are less likely to benefit[1]. The ISSN also concludes that part of its effect seems to be placebo-driven[1].

Does bicarb work for runners?

Across sports, research suggests a small benefit in hard efforts lasting about 30 seconds to 12 minutes[1]. In running, the only meta-analysis, of 11 trials mostly under 5 minutes, found a small benefit that became negligible and not statistically significant once stomach-related dropouts and likely unpublished studies were allowed for; in the eight men-only studies it was small and statistically significant[2]. There is little evidence for longer running[17][18], and we found no marathon or ultra trials[2].

800 m to 5K (Studied)

The classic running trials were small. Six trained middle-distance runners ran 800 m 2.9 seconds faster after bicarb[13], six 400 m runners were 1.52 seconds faster than after a placebo or nothing[12], and club to national standard runners ran simulated 1500 m races in 253.9 against 256.8 seconds[14]. In a treadmill sprint to exhaustion, 15 male endurance runners lasted 82.3 seconds after bicarb against 77.4 after a placebo[25].

Not all were positive. In 15 healthy men, bicarb did not significantly lengthen a run to exhaustion[26], and trained women ran 600 m in 121.5 seconds after bicarb against 120.4 after placebo, not a significant difference[15]. Elite orienteers ran a 3.5 km time trial 6 seconds faster, 775.5 against 781.4 seconds, with bicarb timed to each athlete's own peak[16].

Expectation plays a part: in 1,000 m time trials, runners given a placebo they were told was bicarb improved by 1.5%, against 1.7% with bicarb itself[1].

10K to half marathon (Limited research)

Two small trials had trained runners hold a hard pace for 30 minutes and then run to exhaustion, and neither found that bicarb helped them last longer[17][18]. Of two more running trials lasting close to 30 minutes, the ISSN reports that one, in 7 men from various sports, found bicarb delayed fatigue[2][1].

A meta-analysis of 189 studies found positive average effects for efforts longer than 10 minutes as well as shorter ones, but it pooled many sports, not just running[4]. We found no trials timing a half marathon.

Marathon (Not studied)

We found no controlled trials of bicarb in marathon running. The running tests in the 2025 meta-analysis lasted between 1 and 30 minutes[2]. The nearest evidence is from cycling: bicarb taken before and during a 3-hour simulated race improved power in a 90-second sprint at the end[19].

Ultra (Not studied)

We found no controlled trials of bicarb in ultra running. The same meta-analysis covered tests of 30 minutes or less[2]. Gut problems are already common in distance running, affecting an estimated 30 to 90% of distance runners[27]. In a 161 km race, 60% of runners had nausea or vomiting, and their intake of buffered sodium supplements was no different from that of runners without symptoms[28].

Study by study

The main studies on this page. What they took is what the study gave, not advice for any individual.
StudyWho took partWhat they tookWhat was measuredWhat they found
Miller 2025 [2]Meta-analysis11 crossover trials, 126 people (84% men), mostly competitive runnersOne serving, usually 0.3 g per kg, 60 to 146 minutes beforeContinuous running tests of 1 to 30 minutes (median 4)Small benefit as reported (SMD 0.32); negligible and not significant after adjustment (0.18). Stomach symptoms 29.5% v 2.6%.
de 2022 [4]Meta-analysis189 studies, 2,019 participants, many sportsBicarb and other buffering supplementsExercise capacity and performance; blood bicarbonateBlood bicarbonate up about 5 mmol per litre; positive overall effect (effect size 0.17), with bicarb the most effective buffer
Saunders 2022 [29]Meta-analysis11 studies reporting women separatelyBicarb as each study gave itBlood bicarbonate and performance in womenBlood bicarbonate up 7.4 mmol per litre; pooled effect 0.37, with a credible interval of -0.06 to 0.92
Goldfinch 1988 [12]Randomised controlled trial6 trained male 400 m runners0.4 g per kg in a drink400 m race time1.52 seconds faster than placebo or no supplement
Wilkes 1983 [13]Randomised controlled trial6 male middle-distance runners0.3 g per kg in water800 m race time2.9 seconds faster with bicarb
Bird 1995 [14]Randomised controlled trial10 club to national standard male runners0.3 g per kg in diluted orange juice, about 90 minutes beforeSimulated 1500 m race253.9 v 256.8 seconds with placebo; two runners with stomach ache or diarrhoea did not improve
Tiryaki 1995 [15]Randomised controlled trialTrained women: 11 track athletes and 4 non-athletes0.3 g per kg about 2.5 hours before600 m run121.5 seconds with bicarb v 120.4 with placebo, not significant
Van 2004 [25]Randomised controlled trial15 competitive male endurance runnersBicarb, citrate, lactate or a salt placebo at matched doses, in capsulesTreadmill run to exhaustion lasting 1 to 2 minutes82.3 v 77.4 seconds with placebo, about 2.7% in time-trial terms
Lassen 2021 [16]Randomised controlled trial21 elite orienteers (13 men, 8 women)0.3 g per kg in enteric-coated capsules, timed to each athlete's peak (60 to 180 minutes)3.5 km running time trial775.5 v 781.4 seconds with placebo, with the gain in the second half
Potteiger 1996 [17]Randomised controlled trial7 male competitive distance runners0.3 g per kg in capsules, about 2 hours before30 minutes at lactate-threshold pace, then to exhaustion at 110% of itNo significant improvement
Freis 2017 [18]Randomised controlled trial18 of 25 randomised trained runners analysed (17 men, 1 woman)0.3 g per kg in 700 ml of water, drunk over an hour starting 90 minutes before30 minutes at 95% of anaerobic threshold, then to exhaustion; graded testTime to exhaustion 39.6 v 39.3 minutes, not significant; maximum speed 17.4 v 17.1 km/h, significant. All 7 dropouts had stomach side effects.
Hilton 2020 [5]Randomised controlled trial11 trained male cyclists0.3 g per kg in enteric-coated or gelatin capsules, or placebo, timed to each rider's peak4 km cycling time trial8.5 s and 9.6 s faster than placebo; stomach symptoms in 3 riders v 7
Shannon 2024 [6]Randomised controlled trial14 trained male cyclists0.3 g per kg as mini-tablets in a carbohydrate hydrogel (Maurten Bicarb System), timed to each rider's peak40 km cycling time trialAbout 54 seconds faster than placebo; no difference in total stomach symptomsFunding: The maker, Maurten AB, supplied the product free; one author later joined it. The paper says Maurten had no input
Driller 2012 [30]Randomised controlled trial8 well-trained male cyclistsAcute loading on the day, 3 days of split doses, or placebo4-minute cycling test (average power)3.3% (acute) and 2.3% (serial) higher than placebo, not significantly different from each other
Edge 2006 [21]Randomised controlled trial16 recreationally active womenBicarb or placebo before each session of 8 weeks of cycle interval trainingLactate threshold and time to fatigue, tested without bicarbLarger gains with bicarb: lactate threshold 26% v 15%, time to fatigue 164% v 123%

The key studies, in order

  1. 1983Trial6 trained middle-distance runners ran 800 m 2.9 s faster after bicarb. [13]
  2. 1988Trial6 trained male 400 m runners ran 1.52 s faster after bicarb than after placebo or nothing. [12]
  3. 1995TrialRunners were about 3 s faster in simulated 1500 m races after 0.3 g/kg than after placebo. [14]
  4. 1995TrialTrained women ran 600 m in 121.5 s after bicarb and 120.4 s after placebo, not significant. [15]
  5. 1996Trial7 male runners held lactate-threshold pace for 30 minutes, then ran to exhaustion: no significant improvement. [17]
  6. 2004Trial15 male endurance runners lasted 82.3 s in a treadmill sprint after bicarb, against 77.4 s after placebo. [25]
  7. 2006Trial16 women: bicarb before 8 weeks of interval sessions gave larger gains in lactate threshold and time to fatigue. [21]
  8. 2010Trial8 men ran 20 treadmill repeats of 24 s, then to exhaustion: no significant difference from placebo. [20]
  9. 2012Trial8 cyclists: acute and 3-day split loading raised 4-minute power 3.3% and 2.3% against placebo. [30]
  10. 2012Trial8 men: taking 0.3 g/kg 60, 120 or 180 minutes before sprints didn't change results; discomfort was lowest at 180. [36]
  11. 2013Trial11 endurance-trained adults: one 0.3 g/kg serving raised diastolic, not systolic, pressure (3.3 mmHg); 10 had diarrhoea. [38]
  12. 2013Trial8 trained male cyclists and triathletes: 0.3 g/kg before rides on 5 days in a row lengthened time to exhaustion 23.5%. [32]
  13. 2014Expert reviewEstimates that 30 to 90% of distance runners have exercise-related gut problems. [27]
  14. 2015Trial15 men: 0.3 g/kg raised anaerobic energy release but did not significantly lengthen a run to exhaustion. [26]
  15. 2016Observational study161 km race: 60% had nausea or vomiting; buffered sodium supplement intake did not differ by symptoms. [28]
  16. 2016Trial16 men: the rise in blood bicarbonate and its time to peak (75 to 180 minutes at 0.3 g/kg) varied widely. [24]
  17. 2017Trial18 of 25 trained runners finished: no longer time to exhaustion after 30 minutes of hard running; a small rise in maximum speed. [18]
  18. 2017Meta-analysis40 beta-alanine studies: overall effect 0.18; beta-alanine with bicarb gave the largest effect against placebo, 0.43. [22]
  19. 2018ConsensusFew supplements, including caffeine, creatine, nitrate and bicarb, have good evidence. Contamination is an anti-doping risk. [9]
  20. 2020Trial23 elite rowers were 2 s faster over 2,000 m with bicarb timed to their own peak than at 60 minutes. No placebo. [37]
  21. 2020Non-randomised trial13 men: time to peak was not reproducible; modelling put blood bicarbonate 5 mmol/L up from about 75 to 240 minutes in over 80%. [34]
  22. 2020Trial11 trained male cyclists rode 4 km 8.5 s (enteric-coated) and 9.6 s (gelatin) faster than placebo; 3 v 7 had stomach symptoms. [5]
  23. 2020Trial14 trained men: enteric-coated capsules caused milder stomach symptoms than gelatin ones, though bicarbonate rose less. [39]
  24. 2021Trial11 trained male cyclists: bicarb before and during a 3-hour race raised power in a final 90 s sprint about 3%. [19]
  25. 2021ConsensusImproves high-intensity exercise lasting about 30 s to 12 min; 0.3 g/kg looked optimal. Stomach symptoms were the main side effect. [1]
  26. 2021Expert reviewOnly 1 of 8 studies found an added benefit from combining caffeine and bicarb. [23]
  27. 2021Trial21 elite orienteers ran 3.5 km 6 s faster with bicarb timed to each athlete's own peak (60 to 180 minutes). [16]
  28. 2021Non-randomised trial10 men: 0.3 g/kg in small capsules peaked at 94 minutes, against 121 to 141 minutes in larger capsules. [35]
  29. 2022Meta-analysis189 studies: buffers raised blood bicarbonate about 5 mmol/L with a positive overall effect (0.17); sodium bicarbonate was the most effective. [4]
  30. 2022Meta-analysis11 studies reporting women separately: blood bicarbonate rose 7.4 mmol/L; pooled effect 0.37 (credible interval -0.06 to 0.92). [29]
  31. 2023Trial14 male athletes: PR Lotion improved sprints 2% without changing blood acid-base balance. [43]
  32. 2024Trial12 cyclists at rest: the Maurten Bicarb System peaked sooner than capsules, with much less stomach discomfort. Authors funded by the maker. [40]
  33. 2024Trial10 cyclists: the Maurten Bicarb System cut 3.5 and 4.1 s from two 4 km time trials against placebo. Partly funded by the maker, which one author now works for. [31]
  34. 2024Trial10 soccer players: bicarb capsules improved repeated sprints; a bicarb lotion (PR Lotion) did not. [7]
  35. 2024Trial14 trained male cyclists rode 40 km about 54 s faster with bicarb mini-tablets in a hydrogel; stomach symptoms similar to placebo. [6]
  36. 2025Trial30 female and male athletes: bicarbonate and power responses differed by sex and amount; stomach upset seemed to harm performance. [33]
  37. 2025Meta-analysis11 running trials, 126 people: a small benefit became negligible after adjusting for stomach-related dropouts and publication bias. [2]
  38. 2026Survey66 team-sport practitioners: 91% knew of bicarb and 33% of those used it; fear of stomach upset was the main barrier. [11]
  39. 2026Systematic review101 studies: 0.2 to 0.4 g/kg caused mild to severe stomach symptoms; ways to reduce them were never compared directly. [10]

Who has the research been done in?

Most of the research was done in young men. In the running meta-analysis, 84% of the 126 participants were men, average ages ranged from 20 to 31, and most were competitive runners[2]. Across the wider bicarb literature, only about 20% of studies included women[29].

Benefits have been reported from untrained people to elite athletes, and training status did not seem to explain the studies with no effect[1]. Stomach upset adds to the variation: in one cycling study, the benefit was significant only without the 4 of 21 men who had stomach discomfort[1].

The findings may not apply to masters or teenage runners, as average ages in the running trials ranged from 20 to 31[2], or to people with high blood pressure, kidney problems or a salt-restricted diet, who were excluded from at least one trial[5]. The hydrogel trials and the two multi-day trials described here were in cyclists or triathletes[31][6][30][32].

What we know about women

The evidence in women is thin. Of 149 bicarb studies, only 11 reported results for women separately. In those, blood bicarbonate rose by 7.4 mmol per litre and the pooled effect on performance was 0.37, with a credible interval running from just below zero to 0.92; the authors judged the effect likely small to medium and saw no case for different amounts for women[29]. In running, the benefit was clearer in men-only studies, which the meta-analysis authors called hypothesis-generating[2].

In 30 female and male athletes, the rise in blood bicarbonate and the effect on sprint power differed by sex[33]. Trained women ran 600 m no faster after bicarb[15], while women who took it before 8 weeks of interval sessions gained more than a placebo group[21]. The effect of the menstrual cycle hasn't been studied enough to say[1]. We found no research on bicarb for performance in pregnancy; for antacids, the NHS says to always get advice first when pregnant or breastfeeding[8].

What the research can't tell us yet

The only running meta-analysis pooled 11 small crossover trials, and its small raw benefit did not survive adjustment for stomach-related dropouts and likely unpublished studies; only the eight men-only studies still showed a small, statistically significant benefit[2].

Responses vary widely between people, including how far and how fast blood bicarbonate rises, so the same amount can have quite different effects in different runners[24][9].

Several running trials measured time to exhaustion on a treadmill rather than race times[17][18]. The meta-analysis authors judged most of the running trials too small to detect even large effects, and only 6 of 11 reported stomach symptoms[2].

Blinding is hard, because bicarb tastes salty and bitter[1]. Hydrogel delivery has not been tested in a running trial[2], and the effects of regular use on the kidneys are unknown[1].

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How and when is bicarb used in studies?

Most running studies used 0.3 g per kg of body mass, taken 60 to 146 minutes before the test, as a powder or in capsules with water or juice, usually without food[2]. For a 60 kg runner that is 18 g, which in capsules means swallowing a large number of them[1].

The ISSN position stand describes 0.2 g per kg as the minimum single amount that seems to be needed to improve performance. Amounts above 0.3 g per kg added no benefit and caused more side effects, and 0.1 g per kg did not help[1].

Some studies spread the intake over 3 to 7 days before the test, split across meals, which may lower the risk of stomach problems on the day[1]. These used 0.4 or 0.5 g per kg a day, for example 0.1 to 0.2 g per kg at breakfast, lunch and dinner; several studies found 0.3 g per kg a day did not help[1].

Because the time to peak blood bicarbonate ranged from about one to three hours between people, some research teams timed it to each athlete's own peak[24][16]. Other approaches studied include taking it with a high-carbohydrate meal and using enteric-coated capsules[1] or a hydrogel[6].

When studies gave it

In most single-serving studies, bicarb was taken 60 to 180 minutes before exercise[1]; in the running trials, 60 to 146 minutes, median 90[2]. When 13 men took 0.3 g per kg three times, time to peak was not reproducible, but modelling estimated that in over 80% of people blood bicarbonate stays at least 5 mmol per litre above baseline from about 75 to 240 minutes[34]. Small capsules peaked sooner than larger ones, at 94 against 121 to 141 minutes[35], and discomfort was lowest 180 minutes after taking it[36].

Elite rowers were 2 seconds faster over 2,000 m with bicarb timed to their own peak rather than taken 60 minutes before, but there was no placebo trial[37]. In cycling, a hard warm-up ending 10 minutes before a time trial reduced the benefit in one study, but not in another that allowed 30 minutes' recovery[1].

Multi-day loading usually stopped the evening before, with nothing taken on the day[1]. In cyclists, 3 days of split doses improved a 4-minute test by 2.3%, against 3.3% for a single serving on the day, a difference that was not significant[30]. Taking 0.3 g per kg before rides on 5 days in a row made average time to exhaustion 23.5% longer than placebo[32].

What studies used. These are research protocols, not advice for any individual.
What studies usedWhenRef.
0.3 g per kg of body mass in most running trials (range 0.2 to 0.4)60 to 146 minutes before the test[2]
0.2 g per kg (lowest effective) to 0.3 g per kg (optimal) in one serving60 to 180 minutes before exercise (ISSN guidance)[1]
0.4 to 0.5 g per kg a day, split across mealsFor 3 to 7 days before the test[1]
0.3 g per kg in enteric-coated or gelatin capsulesTimed to each rider's own peak blood bicarbonate[5]
0.3 g per kg once a dayBefore exercise on 5 days in a row[32]
0.15 g per kg before and 0.15 g per kg during exerciseSplit around a 3-hour simulated cycling race[19]

What are the side effects, and who should be careful?

Stomach problems are the main side effect: bloating, nausea, vomiting and stomach pain, with belching and bloating caused by carbon dioxide formed in the stomach[1]. In the six running trials that reported them, 29.5% of people had stomach symptoms after bicarb against 2.6% after placebo; in nine trials, 8.7% dropped out because of them, against 1.6% with placebo[2].

In one trial of endurance-trained adults, 10 of 11 had diarrhoea after a single serving[38]. Symptoms appear to rise with the amount taken at once[10] and can cancel out any benefit: in a 1500 m trial, the two runners who didn't improve both had stomach ache or diarrhoea[1].

Enteric-coated capsules, mini-tablets in a carbohydrate hydrogel and spreading intake over several hours have all been studied as ways to reduce symptoms, but no study has compared them directly[10]. Enteric-coated capsules caused milder symptoms than gelatin ones in 14 trained men, though blood bicarbonate rose less[39]. At rest, the hydrogel system caused much less discomfort than capsules in 12 cyclists, in a study whose authors had funding from the maker[40]. Taking bicarb with a high-carbohydrate meal gave the fewest symptoms in one comparison[1].

Bicarb is about 27% sodium, so the amounts used in studies add far more sodium than the US upper limit of 2,300 mg a day[38]. In endurance-trained adults, one serving did not change systolic blood pressure, but diastolic pressure rose by about 3 mmHg and heart rate by about 10 beats a minute[38].

Medicines and health conditions

Sodium bicarbonate is an ingredient in some antacids. The NHS says antacids can affect how well other medicines work, and advises not taking other medicines within 2 to 4 hours of an antacid[8].

The NHS says some antacids may not be safe with liver disease, kidney disease or heart failure, and that some are high in sodium, which matters for people who need to control their salt intake, such as those with high blood pressure or cirrhosis[8]. It advises adults to have no more than 6 g of salt a day[41]. A 0.3 g per kg serving for a 60 kg runner is 18 g of sodium bicarbonate, about 27% sodium[38].

Trials can leave these groups out: one excluded people with high blood pressure, kidney problems or a salt-restricted diet[5]. The ISSN says the effects of regular use on kidney function are not yet known[1].

Be careful if

  • You have high blood pressure or have been told to cut down on salt: the amounts studied are high in sodium[38][41].
  • You have kidney or liver disease or heart failure: the NHS says some antacids may not be safe with these[8], and the ISSN says bicarb's effects on kidney function aren't yet known[1].
  • You take other medicines: the NHS says antacids can affect how well other medicines work[8].
  • You have a sensitive stomach or a gut condition: stomach symptoms are common[2].
  • You are pregnant or breastfeeding: the NHS says to get advice before taking antacids[8].
  • You plan to use it in a race: the IOC consensus statement says supplements should be trialled in training before they are used in competition[9].

Is bicarb allowed in competition?

Sodium bicarbonate is not on the World Anti-Doping Agency's Prohibited List, so it is permitted in competition[42].

The anti-doping risk with any supplement is contamination. Products can contain prohibited substances that aren't on the label, and under the World Anti-Doping Code an athlete is responsible for anything found in their sample, even if it got there by accident[9].

Independent quality-assurance schemes, often called batch testing, check supplement products for prohibited substances[9]. WADA says using a product from one of these schemes can reduce, but not eliminate, the risk of an anti-doping violation[42], and the IOC says no product can be guaranteed entirely safe[9].

Myth or evidence?

5 things runners hear about sodium bicarbonate. Pick an answer to see what the research says.

  1. 1.Bicarb helps in any race, as long as you take enough.

    Show the answer

    Myth. Its effects are clearest in hard efforts of about 30 seconds to 12 minutes, and amounts above 0.3 g per kg added no benefit but caused more side effects[1].

  2. 2.Stomach problems are common after taking bicarb.

    Show the answer

    Evidence. In the six running trials that reported them, 29.5% of people reported stomach symptoms after bicarb, against 2.6% after a placebo[2].

  3. 3.Bicarb is banned in athletics.

    Show the answer

    Myth. Sodium bicarbonate is not on the WADA Prohibited List[42].

  4. 4.The same amount works the same way for every runner.

    Show the answer

    Myth. How far blood bicarbonate rises, and when it peaks, varies widely from person to person[24].

  5. 5.Bicarb makes a clear difference over the marathon distance.

    Show the answer

    Myth. We found no controlled trials in marathon running; the running trials in the 2025 meta-analysis lasted 1 to 30 minutes[2].

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Frequently asked questions

Does bicarb work for runners?
For short, hard races there is some evidence: runners were about 3 seconds faster over 1500 m in one trial[14]. Across running trials, most lasting under 5 minutes, a 2025 meta-analysis found the average benefit negligible once likely publication bias was allowed for, and stomach symptoms were common[2].
Does bicarb help in a marathon?
There is no direct evidence: the running trials in the 2025 meta-analysis lasted 1 to 30 minutes[2]. After 30 minutes at a hard pace, bicarb did not help trained runners last longer[17][18].
How common are stomach problems with bicarb?
Common. In the six running trials that reported them, 29.5% of people reported stomach symptoms after bicarb, against 2.6% after a placebo[2]. In one trial, 10 of 11 adults had diarrhoea[38].
Is bicarb banned in athletics?
No. Sodium bicarbonate is not on the WADA Prohibited List[42]. The risk is contamination: a product can contain a banned substance that isn't on the label, and athletes are responsible for anything found in their sample[9].
How long before exercise do studies give bicarb?
Most running studies gave it 60 to 146 minutes before the test[2], and the ISSN position stand describes 60 to 180 minutes[1]. The time to peak blood bicarbonate varies a lot from person to person[24].
Do capsules or gels reduce the stomach problems?
In small studies, yes. Enteric-coated capsules caused milder symptoms than gelatin capsules[39], and a hydrogel system caused less discomfort than capsules[40], but no study has compared all the options directly[10].
Does bicarb cream work?
The evidence is weak. In 10 soccer players, capsules improved repeated sprints but a bicarb lotion did not[7]. In another trial the lotion improved sprints by 2% without changing blood acid-base balance, so how it could work is unclear[43].
Does bicarb work for women?
There is less evidence than for men. In 11 studies reporting women separately, the pooled effect was 0.37, judged likely small to medium, though its credible interval included zero[29]. In running, the benefit was clearer in men-only studies[2].
Can bicarb be taken over several days instead of on race day?
Yes, some studies did this. They gave 0.4 to 0.5 g per kg a day, split into smaller amounts, for 3 to 7 days, usually stopping the evening before[1]. In cyclists, 3 days of split doses improved a 4-minute test about as much as a single serving on the day[30].
Does bicarb work better with caffeine?
There's little evidence that it does. Only 1 of 8 studies found an added benefit from combining them[23], and the ISSN position stand calls the combination's effect unclear[1].
Does bicarb work better with beta-alanine?
Possibly. In a meta-analysis of beta-alanine studies, taking it with bicarb gave the largest effect against placebo, 0.43 against 0.18 for beta-alanine overall[22], but several studies found no added benefit[1].
How much sodium is in a bicarb dose?
A lot. Sodium bicarbonate is about 27% sodium, so the amounts used in studies add far more sodium than the US upper limit of 2,300 mg a day[38]. For comparison, the NHS says adults should have no more than 6 g of salt a day[41].

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Who wrote and reviewed this

Written by Grant MacMillan, Editor, RunV. Not yet reviewed by an expert.

Last checked against its references . Next review due . How pages are reviewed · How we grade research

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